| Zenit | |
| Manufacturer: | OKB-1 |
| Country: | Soviet Union |
| Applications: | Photo reconnaissance |
| Operator: | Soviet space program |
| Derivedfrom: | Vostok |
| Status: | Retired |
| Launched: | 688 |
| Lost: | 21 |
| First: | 11 Dec 1961 Zenit 2-1 |
| Last: | 7 Jun 1994 Kosmos 2281 |
| Lastretired: | 8 Nov 2004 Zenit 8-103 |
Zenit (Russian: link=no|Зени́т, pronounced as /ru/, Zenith) was a series of military photoreconnaissance satellites launched by the Soviet Union between 1961 and 1994. To conceal their nature, all flights were given the public Kosmos designation.
The basic design of the Zenit satellites was similar to the Vostok crewed spacecraft, sharing the return and service modules. It consisted of a spherical re-entry capsule 2.3m (07.5feet) in diameter with a mass of around 2400kg (5,300lb). This capsule contained the camera system, its film, recovery beacons, parachutes and a destruct charge. In orbit, this was attached to a service module that contained batteries, electronic equipment, an orientation system and a liquid-fuelled rocket engine that would slow the Zenit for re-entry, before the service module detached. The total length in orbit was around 5m (16feet) and the total mass was between 4600kgand4740kgkg (10,100lband10,450lbkg).
Unlike the American CORONA spacecraft, the return capsule carried both the film and the cameras and kept them in a temperature-controlled pressurised environment. This simplified the design and engineering of the camera system but added considerably to the mass of the satellite. An advantage was that cameras could be reused. The camera would either land on the ground or be recovered in midair by a modified Mil Mi-8 helicopter.[1]
Early Zenits were launched using the Vostok rocket; later versions used the Voskhod and the Soyuz rockets. The first flights were launched from Baikonur Cosmodrome but subsequent launches also took place at Plesetsk Cosmodrome.
Most Zenits flew in a slightly elliptical orbit with a perigee of around 200km (100miles) and an apogee between 250and; the missions usually lasted between 8 and 15 days.
In 1956, the Soviet government issued a secret decree that authorised the development of "Object D" which led to the program to launch Sputnik 3 (Sputnik 1 was a simplified spin-off of the Object D program.) The text of the decree remains secret, but it apparently authorised another satellite program – "Object OD-1" – which was to be used for photo-reconnaissance from space.
By 1958, the OKB-1 design bureau was simultaneously working on Object OD-1 and Object OD-2 – an early design for the Vostok crewed spacecraft. The development of Object OD-1 was experiencing serious difficulties so the head of OKB-1, Sergei Korolev, initiated work to see if a design based on Object OD-2 could be used for an uncrewed photo-reconnaissance satellite. This may have been a political manoeuvre that would enable him to continue the crewed space program and avoid diverting more of OKB-1's resources into Object OD-1.
Despite bitter opposition from the military the Soviet government endorsed Korolev's approach and issued decrees on 22 and 25 May 1959 which ordered the development of three different spacecraft, all based on the same basic, Object OD-2, design. Spacecraft 1K would be a simplified prototype, 2K was to be a reconnaissance satellite and 3K was to be for crewed flights. The name Vostok was also initially used for all three of these craft. But in 1961 the name became publicly known as the name of Yuri Gagarin's spacecraft so the "Vostok 2" reconnaissance satellite was renamed "Zenit 2".
The first Zenit launch attempt took place on 11 December 1961, but there was a fault in the rocket's third stage and the spacecraft was destroyed using its destruct charge. The second attempt — publicly referred to as Kosmos 4 — was successfully launched on 26 April 1962 and re-entered three days later. However a failure in the orientation system meant few useful pictures were obtained; usable pictures had a resolution of about 5 to 7 meters. Launch #3 on 1 June 1962 failed dramatically when one of the 8A92 booster's strap-ons shut down at liftoff and fell onto the pad, exploding on impact. The rest of the launch vehicle crashed 300 meters away. This accident caused considerable damage to Site 1, delaying the flights of Vostok 3 and Vostok 4 by two months.
On 28 July 1962, Site 1 was back in service to host the next Zenit flight, which performed successfully. Testing continued over the next year largely without incident but on 10 July 1963, another launch accident occurred in practically identical fashion to the June 1962 failure. Once again, one of the strap-ons shut down at liftoff, separated from the booster, and exploded on impact with the pad while the rest of the launch vehicle crashed a few hundred feet away.
Examination of telemetry from the booster indicated that some sort of electrical failure occurred, but subsequent investigation took three months and finally concluded that a switch designed to cut power to the strap-ons at staging had malfunctioned, possibly due to liftoff-induced vibration. The electrical circuit in the 8A92 was redesigned and it never again experienced problems with the strap-ons shutting down at launch.
Many versions of the satellite were developed for different reconnaissance missions and flights continued until 1994.
Zenit 2 was the first version to be launched between 1961 and 1970 (there was no Zenit 1).
The arrangement of cameras varied, but most flights carried four cameras of 1000 mm focal length, and one of 200 mm focal length. The single lower resolution camera was intended to provide low-resolution pictures that would help give a context to the high-resolution pictures.
Each camera had 1500 frames of film and from, each frame held an image of a square. The ground resolution was stated to be although some unofficial sources claim it was much better—one source claims the number of cars in a car park could be counted. The cameras were developed at the Krasnogorsk Optical-Mechanical Factory near Moscow. The Krasnogorsk factory, which had been producing a variety of optical equipment for the military since 1942, was also the manufacturer of the popular Zenit SLR cameras.
Zenit 2s also carried ELINT equipment called Kust-12M (bush) to receive NATO radar signals. The satellites carried a parabolic antenna, around in diameter, that is associated with this equipment. However, it is unclear if the antenna transmitted recorded signals to the ground or was for intercepting radar signals. In the latter case they would have been recorded on magnetic tape, to be retrieved after the return capsule landed.
There were 81 Zenit 2 launches. 58 were successful and 11 were partially successful. There were 12 failed missions, 5 because of a satellite malfunction and 7 because of a failure in the launch vehicle.
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Improvements included a new camera system and the addition of solar panels. As the spacecraft mass was increased to 6300 kg, the Vostok rocket was replaced by the Voskhod rocket and Soyuz rockets. In common with Zenit 2 satellites this also had an ELINT payload.
A total of 101 Zenit-2M satellites were launched between 1968 and 1979
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Unlike Zenit 2, little information on Zenit 4 has been released. The Zenit 4 was intended for high-resolution photography and carried one camera of 3000 mm focal length as well as a 200 mm camera. The focal length of the main camera was greater than the diameter of the capsule so the camera made use of a mirror to fold the light path. The ground resolution is not publicly known but it is believed to have been 1–2 metre.
The Zenit 4 had a mass of 6300 kg — around 1800 kg more than the Zenit 2. So, instead of the Vostok rocket, it was launched by the heavier Voskhod rocket. A total of 76 Zenit-4 satellites were flown between 1963 and 1970.
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An improved version of the Zenit 4, the Zenit 4M carried a new camera, solar panels, and a restartable engine so the satellite's orbit could be altered during the course of its mission. The mission duration was 13 days.
A total of 61 Zenit-4M satellites were launched between 1968 and 1974.
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These may have been versions of the Zenit 4 designed specifically to fly in lower orbits to improve image resolution. Some sources claim they were fitted with devices to compensate for aerodynamic drag and to withstand the effects of aerodynamic heating.
A total of 80 Zenit-4MK satellites were launched between 1969 and 1977.
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Intended to replace the 4MK design, the 4MKM may have been a low altitude variant of the later Zenit-6U and have similar equipment to it
| 1 | Kosmos 927 | 12 July 1977 09:00 | 25 July 1977 | 1977-063A | 153 x 361 km | |||
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| 2 | Kosmos 932 | 20 July 1977 07:35 | 2 August 1977 | 1977-069A | 150 x 358 km | |||
| 3 | - | 10 August 1977 10:40 | - | - | (Suborbital) | - | ||
| 4 | Kosmos 938 | 24 August 1977 14:30 | 6 September 1977 | 1977-078A | 181 x 340 km | |||
| 5 | Kosmos 953 | 16 September 1977 14:30 | 29 September 1977 | 1977-089A | 180 x 330 km | |||
| 6 | Kosmos 957 | 30 September 1977 09:46 | 13 October 1977 | 1977-098A | 171 x 361 km | |||
| 7 | Kosmos 964 | 4 December 1977 12:00 | 17 December 1977 | 1977-110A | 171 x 362 km | |||
| 8 | Kosmos 969 | 20 December 1977 15:50 | 3 January 1978 | 1977-120A | 180 x 317 km | |||
| 9 | Kosmos 974 | 6 January 1978 15:50 | 19 January 1978 | 1978-001A | 178 x 334 km | |||
| 10 | Kosmos 986 | 24 January 1978 09:50 | 7 February 1978 | 1978-010A | 172 x 318 km | |||
| 11 | Kosmos 987 | 31 January 1978 14:50 | 14 February 1978 | 1978-013A | 189 x 322 km | |||
| 12 | Kosmos 989 | 14 February 1978 09:30 | 28 February 1978 | 1978-017A | 169 x 318 km | |||
| 13 | Kosmos 993 | 10 March 1978 10:42 | 23 March 1978 | 1978-027A | 190 x 325 km | |||
| 14 | Kosmos 999 | 30 March 1978 07:50 | 12 April 1978 | 1978-033A | 174 x 352 km | |||
| 15 | Kosmos 1003 | 20 April 1978 15:30 | 4 May 1978 | 1978-040A | 178 x 328 km | |||
| 16 | Kosmos 1007 | 16 May 1978 10:40 | 28 May 1978 | 1978-048A | 168 x 350 km | |||
| 17 | Kosmos 1021 | 10 June 1978 08:35 | 23 June 1978 | 1978-057A | 173 x 313 km | |||
| 18 | Kosmos 1022 | 12 June 1978 10:30 | 25 June 1978 | 1978-059A | 171 x 344 km | |||
| 19 | Kosmos 1029 | 29 August 1978 15:00 | 8 September 1978 | 1978-082A | 194 x 316 km | |||
| 20 | Kosmos 1031 | 9 September 1978 15:00 | 22 September 1978 | 1978-085A | 182 x 329 km | |||
| 21 | Kosmos 1042 | 6 October 1978 15:30 | 19 October 1978 | 1978-092A | 179 x 299 km | |||
| 22 | Kosmos 1047 | 15 November 1978 11:45 | 28 November 1978 | 1978-104A | 171 x 354 km | |||
| 23 | Kosmos 1049 | 21 November 1978 12:00 | 4 December 1978 | 1978-107A | 169 x 338 km | |||
| 24 | Kosmos 1059 | 7 December 1978 15:30 | 20 December 1978 | 1978-110A | 180 x 338 km | |||
| 25 | Kosmos 1068 | 26 December 1978 15:30 | 8 January 1979 | 1978-123A | 191 x 389 km | |||
| 26 | Kosmos 1071 | 13 January 1979 15:30 | 26 January 1979 | 1979-002A | 179 x 339 km | |||
| 27 | Kosmos 1073 | 30 January 1979 15:15 | 12 February 1979 | 1979-006A | 182 x 328 km | |||
| 28 | Kosmos 1078 | 22 February 1979 12:10 | 2 March 1979 | 1979-016A | 168 x 280 km | |||
| 29 | Kosmos 1080 | 14 March 1979 10:50 | 28 March 1979 | 1979-023A | 169 x 294 km | |||
| 30 | Kosmos 1098 | 15 May 1979 11:40 | 28 May 1979 | 1979-040A | 170 x 354 km | |||
| 31 | Kosmos 1113 | 10 July 1979 09:00 | 23 July 1979 | 1979-064A | 173 x 330 km | |||
| 32 | Kosmos 1117 | 25 July 1979 15:20 | 7 August 1979 | 1979-068A | 177 x 325 km | |||
| 33 | Kosmos 1120 | 11 August 1979 09:15 | 24 August 1979 | 1979-073A | 170 x 362 km | |||
| 34 | Kosmos 1128 | 14 September 1979 15:30 | 27 September 1979 | 1979-081A | 173 x 328 km | |||
| 35 | Kosmos 1148 | 28 December 1979 13:00 | 10 January 1980 | 1979-106A | 170 x 340 km | |||
| 36 | Kosmos 1165 | 21 February 1980 12:00 | 5 March 1980 | 1980-017A | 170 x 350 km | |||
| 37 | Kosmos 1170 | 1 April 1980 08:00 | 12 April 1980 | 1980-025A | 178 x 379 km | |||
| 38 | Kosmos 1173 | 17 April 1980 08:30 | 28 April 1980 | 1980-029A | 174 x 352 km | |||
| 39 | Kosmos 1214 | 10 October 1980 13:10 | 23 October 1980 | 1980-082A | 170 x 347 km |
Another variant of the Zenit-4 design equipped with a Priroda-3 camera, intended for the investigation of natural resources in the interests of the Soviet economy and international cooperation.
A total of 27 Zenit-4MKT satellites were launched between 1975 and 1985.
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A special version of the Zenit 4M intended for topographical photography. It carried an SA-106 topographic camera, a laser altimeter and Doppler apparatus.
| 1 | Kosmos 470 | 27 December 1971 14:04 | 6 January 1972 | 1971-118A | 192 x 259 km | |||
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| 2 | Kosmos 502 | 13 July 1972 14:30 | 25 July 1972 | 1972-055A | 203 x 262 km | |||
| 3 | Kosmos 541 | 27 December 1972 10:30 | 8 January 1973 | 1972-105A | 218 x 348 km | |||
| 4 | Kosmos 576 | 27 June 1973 11:50 | 9 July 1973 | 1973-044A | 204 x 332 km | |||
| 5 | Kosmos 616 | 17 December 1973 12:00 | 28 December 1973 | 1973-102A | 206 x 332 km | |||
| 6 | Kosmos 664 | 29 June 1974 12:50 | 11 July 1974 | 1974-049A | 205 x 341 km | |||
| 7 | Kosmos 693 | 4 November 1974 10:40 | 16 November 1974 | 1974-088A | 219 x 243 km | |||
| 8 | Kosmos 720 | 21 March 1975 06:50 | 1 April 1975 | 1975-019A | 212 x 273 km | |||
| 9 | Kosmos 759 | 12 September 1975 05:30 | 23 September 1975 | 1975-084A | 231 x 276 km | |||
| 10 | Kosmos 811 | 31 March 1976 12:50 | 12 April 1976 | 1976-030A | 206 x 338 km | |||
| 11 | Kosmos 855 | 21 September 1976 11:40 | 3 October 1976 | 1976-095A | 221 x 321 km | |||
| 12 | Kosmos 916 | 10 June 1977 08:00 | 21 June 1977 | 1977-046A | 255 x 304 km | |||
| 13 | Kosmos 988 | 8 February 1978 12:15 | 20 February 1978 | 1978-015A | 201 x 335 km | |||
| 14 | Kosmos 1046 | 1 November 1978 12:00 | 13 November 1978 | 1978-102A | 202 x 324 km | |||
| 15 | Kosmos 1069 | 28 December 1978 16:30 | 10 January 1979 | 1978-124A | 254 x 289 km | |||
| 16 | Kosmos 1119 | 3 August 1979 10:45 | 15 August 1979 | 1979-071A | 213 x 245 km | |||
| 17 | Kosmos 1139 | 5 October 1979 11:30 | 18 October 1979 | 1979-088A | 199 x 329 km | |||
| 18 | Kosmos 1180 | 15 May 1980 05:35 | 26 May 1980 | 1980-038A | 245 x 279 km | |||
| 19 | Kosmos 1211 | 23 September 1980 10:30 | 4 October 1980 | 1980-077A | 211 x 236 km | |||
| 20 | Kosmos 1239 | 16 January 1981 12:00 | 28 January 1981 | 1981-004A | 210 x 231 km | |||
| 21 | Kosmos 1309 | 18 September 1981 09:30 | 1 October 1981 | 1981-092A | 212 x 257 km | |||
| 22 | Kosmos 1332 | 12 January 1982 12:30 | 25 January 1982 | 1982-002A | 207 x 251 km | |||
| 23 | Kosmos 1398 | 3 August 1982 11:30 | 13 August 1982 | 1982-077A | 211 x 231 km |
A "universal" version of the Zenit, intended for both low-altitude, high-resolution missions and higher-altitude, general observation missions. All flights used the Soyuz launch vehicle. There were a total of 97 Zenit-6U satellites launched between 1976 and 1984.
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This was intended for military cartographic photography. It used a Soyuz launch vehicle and launches took place from both Baikonur and Plesetsk. It had a 15-day orbital life. Similar satellites were referred to using the "Resurs-DK No.1" designation.
A total of 102 Zenit-8 satellites were launched between 1984 and 1994, in addition to one sent into a suborbital trajectory during the maiden flight of the Soyuz-2 rocket in 2004.
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A Zenit satellite was mentioned in the movie .